51.In which situation would a CPA be in violation of the rules of professional ethics in determining professional fees?

A.A fee that is based on 10% of the client's adjusted net income for the current year.

B.A fee which is lower compared to the fee charged in the prior year for similar services.

C.A fee based on appropriate rates per hour or per day for the time of each person engaged inperforming professional services.

D.A fee based on appropriate rates per hour, where the appropriate rate is based on the

why letter A is correct and why other letters are wrong?